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Core logging guide Proceedings of the Symposium on Exploration for Rock Engineering Johannesburg November Page - A guide to core logging for rock engineering Core Logging Committee of the South Africa Section of The Association of Engineering Geologists S

Proceedings of the Symposium on Exploration for Rock Engineering Johannesburg November Page - A guide to core logging for rock engineering Core Logging Committee of the South Africa Section of The Association of Engineering Geologists SUMMARY A guide for the logging of borehole core for rock engineering purposes is proposed General acceptance of such a guide ensures that core logs will generally contain meaningful descriptions of the rock mass parameters most signi ?cant in rock engineering problems The use of de ?ned terms and format ensures that any reader of the log will have an appreciation of the original appearance of the core and in particular those aspects important to rock engineering The proposed guide takes due cognizance of existing accepted systems of soil and rock mass description or classi ?cation and attempts to remain compatible with these wherever feasible Only those parameters which are commonly of interest in rock engineering are described Qualitative descriptions depending only on visual inspection and simple mechanical ?eld tests are used Primary core descriptions include descriptions of colour weathering fabric discontinuity surface spacing hardness rock name and stratigraphic horizon This is followed where required by a description of the discontinuity surfaces including their type separation fracture ?lling presence or absence roughness and orientation If signi ?cant an additional description of the nature of the fracture ?lling including moisture colour consistency or hardness soil or rock type and origin is added The signi ?cance of each of these parameters with respect to engineering behaviour is discussed and standard descriptive terms de ?ned Other information commonly recorded on the borehole log such as drilling method and size core recovery RQD fracture frequency and standard tests are reviewed and techniques of presentation are suggested Recommendations are made for the handling and storage of rock cores Some useful techniques for the logging of core are discussed INTRODUCTION The purpose of the Core Logging Committee of the South Africa Section of the Association of Engineering Geologists was to prepare a guide for core logging for rock engineering purposes in South Africa For such a guideto be generally accepted it should ful ?l the following requirements a It should be su ?ciently detailed to ensure that the resulting core log contains enough information to enable reliable interpretations of geological androck engineering conditions for mosttypical engineering structures b It should notbe so complex as to renderitsuse impractical or unnecessarily cumbersome c It musttake dueregard of such standardizedprocedures as mayalready exist and wherefeasible incorporate these with a minimum of variations CA guide to core logging for rock engineering A distinction is drawn between the borehole log and the core log The borehole log includes a description of relevant data applicable to the drilling of the borehole and to the core recovered It includes information on the drilling machine tools and materials used progress di ?culties encountered and tests performed Part of the borehole log is the core log which is purely a description of the recovered core It is the corelog whichis